Geological Disposal of Radioactive Waste
Background to the issue
It is known that nuclear power plants produce huge quantities of extremely radioactive materials. Isotopes are responsible for this energy when they split. The final product also generates new nuclear wastes, for instance, U/Pu/Am from spent nuclear fuel. Scholars and professionals have suggested several alternative methods of managing spent nuclear fuel. In most cases, these suggestions have concentrated on direct disposal at geologic siting whereas others have proposed reprocessing spent nuclear fuel (Bunn, Steve Fetter, & van der Zwaan 2003). At the same time, such proposals have also evaluated relative costs associated with direct disposal in land sitings against reprocessing. Such nuclear waste materials continue to be major sources of concern as the industry continues to grow and demands for nuclear power. At a minimum, spent nuclear fuel requires reprocessing to achieve both economic advantages and reduction of costs.
This proposal provides an alternative solution on how a company can utilize further or reprocess U/Pu/Am from spent nuclear fuel.
NuclearRUS is currently experiencing challenges in the management, storage and reuse of its spent nuclear fuel. Nuclear power facilities and reactors run almost on natural, pure uranium. The uranium undergoes a series of chemical fission to release heat and generate radioactive fission elements, consisting of plutonium and other transuranic materials (Feiveson, Mian, Ramana, & von Hippel 2011). The released heat generates steam to power turbines for electricity generation. At the end of the process, these chains of reactions will reach a point where all fuel materials are considered exhausted or spent and therefore cannot generate more energy and must be replaced with new supplies. After the process, extremely hot and radioactive spent nuclear fuel obtained from power reactors is transferred to a pool filled with water next to the reactor to ensure that high temperatures and levels of radiation are contained and controlled immediately. These spent materials may be stored in this pool for a range of a few years to several decades (Office for Nuclear Regulation n.d). Once the spent nuclear fuel has cooled, it may then be transported to a different facility with controlled air temperatures for storage at the site or in an identified common facility in a given location.
However, some countries have adopted reprocessing technologies and constructed plants to ensure that spent nuclear fuel is processed and utilized further. According to the Union of Concerned Scientists, reprocessing is “a series of chemical operations that separates plutonium and uranium from other nuclear waste contained in the used (or “spent”) fuel from nuclear power reactors” (Union of Concerned Scientists, n.d). This process involves the dissolving of fuel to obtain available uranium and plutonium to be possibly used in a reactor again or used for manufacturing nuclear weapons. Reprocessing, to some extent, also generates considerable amount of waste materials with elements from fission and certain radioisotopes released from the spent nuclear fuel. In addition, the process is also responsible for other streams of radioactive waste materials such as plutonium released from the fuel containing plutonium elements.
Generally, nuclear scientists have agreed that spent nuclear fuel and other materials with significantly high levels of radioactive materials from reprocessing and plutonium waste materials must be effectively stored in special facilities for millions of years to reduce chances of such radioactivity containing materials escaping into the environment (IAEA 2005). At the same time, individuals responsible for such waste materials must ensure that they remain safe and no plutonium or any other chemical rich in uranium is acquired for nuclear weapon purposes. On this note, it is recommended that spent nuclear fuel should be deposited inland sitings rather than stored indefinite storage in onsite facilities.
In several countries, the initially favored idea was geological repository (Feiveson et al. 2011). This method was believed that it would separate people, the environment and the spent nuclear fuel wastes and therefore reduce exposure to radioactive waste elements. Many advanced countries had focused on the use of salt beds due to their ability to sell themselves. Clay beds were also favored for the same reason. In other countries, hard granite rocks with cracks cannot allow for deep disposals of spent nuclear fuels. Any potential cracks were agents for leakage of toxic waste materials from the site (Feiveson et al. 2011). In countries with disposal challenges, such as Sweden, they have developed thick copper cask that can withstand storage and not corrode for more than millions of years (Jasper, 1990). These are all alternatives of disposing of spent nuclear fuel, which has encountered challenges during their implementation processes. For instance, manmade water channels are known to penetrate through salt beds. At the same time, copper may also erode at a significantly higher rate than initially believed. In this regard, only suitable geology characteristics and technical approaches from engineers may work to prevent leakages of spent nuclear fuel to the environment.
The above-mentioned approaches of disposing of spent nuclear fuel have shown their weaknesses and uncertainties in long-term performance. On this note, many have argued that reprocessing or utilizing further spent nuclear fuel could be the most favorable approach for the future (Jasper 1990). However, if these waste materials are disposed of underground for a limited period, then the strategy could even complicate the safeguard of radioactive waste materials (Feiveson et al. 2011).
Proposal of a method for waste stream
The proposed solution for NuclearRUS to handle spent nuclear fuel is reprocessing based on advanced technology of PUREX (plutonium and uranium extraction) proposed by the World Nuclear Association (2015) and the International Atomic Energy Agency (n.d). In addition, other approaches such as CARBEX Process could be even more effective than the PUREX technique (Stepanov et al. 2011). CARBEX Process was however not chosen because it has not been widely used. However, it is imperative to note that nuclear scientists must review and adapt many of these approaches to meet the unique characteristics of processes and chemical contents of spent nuclear fuel. This is performed to prevent process technicalities, the necessary resource and expertise required to implement them effectively.
As previously defined and demonstrated, reprocessing involves further extraction of useful plutonium and uranium for further use in nuclear power plants and possibly in nuclear weapons (Union of Concerned Scientists n.d). This is unique advantage, which is derived from spent nuclear fuel. It offers fresh fuel for today and future use. However, processes must be developed to meet reprocessing needs (Feiveson et al. 2011). Therefore, policymakers must formulate policies that support reprocessing of spent nuclear fuel to support sustained usage, conservation and efficient energy consumption.
Reprocessing has been in existence since the 1960s but was obviously restricted with limited technologies and expertise. As a result, nuclear power plants did not favor it. Today, however, technologies, expertise, and facilities have been developed to meet such unique challenges from spent nuclear fuel.
Currently, the most common reprocessing technique in many plants is the PUREX2 process. The technology originated from the military programs and experiences in their attempts to develop nuclear weapons (Glatz 2012). The process is thorough and involves the use of several chemicals to chop spent nuclear fuel in order to extract plutonium and uranium. It has been observed that the two most vital materials in the spent nuclear fuel are highly-selective but are separated in the process from other fission elements, including actinides. Actinides are retained in the first acid content used for dissolving the waste materials.
The next stages involve the separation of uranium and plutonium. These materials are then purified in order to obtain at least 99.9% of uranium and plutonium. Hence, PUREX process aims for absolute purity and total elimination of highly radioactive contents. In some extraction procedures using the PUREX technique, “both uranium and plutonium may be processed together to avoid obtaining pure plutonium” (International Atomic Energy Agency n.d). This reprocessing approach is utilized in Japanese plant at Rokkasho. Other materials such as fission elements, actinides and activation contents are “processed and vitrified , i.e. mixed with glass material to form a borosilicate glass, and encapsulated in a steel container” (International Atomic Energy Agency n.d).
In short, a reprocessing policy can be applied to ensure that the PUREX process delivers the best outcomes. The courses for reprocessing may vary significantly based on the contents and levels of waste materials. Nevertheless, a company may adopt any of the courses provided by the World Nuclear Association (2015) to meet reprocessing needs.
- Separate U, Pu, (as today)
- Separate U, Pu+U (small amount of U)
- Separate U, Pu, minor actinides
- Separate U, Pu+Np, Am+Cm
- Separate U+Pu all together
- Separate U, Pu+actinides, certain fission products
The current PUREX process ensures that the resultant uranium (Reprocessed Uranium/RepU) is enriched. On the other hand, plutonium will be delivered directly to the mixed oxide for fuel production. It has been however observed that this approach presents two critical challenges. First, the purely separated plutonium remains potentially dangerous because of proliferation. Second, there are traces of actinides that remain in the waste materials after separation. This situation creates stable plutonium with longer life relative to one combined with fission elements only.
It has been observed that traces of actinides are almost impossible to destroy while light water reactors recycling methods provide only partial waste management advantages (International Atomic Energy Agency n.d; von Hippel 2001). It is believed that developments in technologies would ensure that the PUREX process could deliver final waste without traces of actinides. Further, it would decompose them alongside reprocessed plutonium and uranium within the fast neutron reactors. At the same time, it is expected that fission products with longer life could also be eliminated from waste materials using such new developments. Once these new technologies are implemented, they would offer effective reprocessing and recycling processes in reactors. They will mark a critical stage in the development of advanced spent nuclear fuel management. Thus, PUREX process would deliver widespread use through these new approaches. Improvements must strive to instill sustainability through reactor systems. This can only take place when the number of waste materials discharged is minimized by enhanced recycling methods for all actinides. The overall achievements can only be reflected in the result of spent nuclear fuel reprocessing. The focus must be driven by finding solutions for actinide solutions (Glatz 2012). It will ensure that a section the process accounts for included aqueous for extraction of traces of actinides. This should extract traces of actinides to demonstrate that these elements could be removed from the final waste. Further, an improved chamber with diamide or phosphine oxide elements can be used to extract other minor traces of actinides. Attention for the new system will focus on an extremely challenging task of separating “lanthanides from other trivalent actinides” (Glatz 2012).
For effective utilization of the method, particularly in pyrometallurgy, only specialists will conduct the procedures because of the complex mechanisms involved in elements extraction (Glatz 2012).
Emerging reactors have been shown to be effective and can extract and recycle all traces of actinides in the waste materials. It is shown that new developments in reprocessing have ensured that countries such as the US have reviewed their policies on spent nuclear fuel recycling because of the promising outcomes they hold. For instance, nuclear societies and other bodies have shown that new developments and subsequent deployment found in advanced nuclear reactors with fast neutron fission capabilities would result in reliability, sustainability and security for energy supply (World Nuclear Association 2015). Reprocessing would enhance the usability of spent nuclear fuel materials by increasing the amount of energy that can generate just from already used uranium. Through the improved PUREX process, nearly all elements with longer life would be extracted at the fast reactor operation and yield only a small quantity of fission product waste materials that require “guaranteed isolation from the environment for not more than 500 years” (World Nuclear Association 2015).
The use of PUREX process may require extensive collaboration, data sharing, shared knowledge, and facilities. The company may need to work with other firms with similar advanced technologies in nuclear waste management to enhance the application of more robust proliferation-resistant recycling technologies in order to generate additional energy from waste materials, reduce waste materials for sitings and lessen cases of proliferation (Ojovan & Lee 2005).
Once NuclearRUS adopts this new technology, it would spend available resources effectively, reduce dependence on fossil fuels and develop new reprocessing facilities with advanced capabilities to assist other countries or companies with limited capacities to handle such materials, for instance, Japan now transfers its spent nuclear fuel to the UK for reprocessing (Matsuura 2013). This would result in two critical developments, including an advanced reprocessing technology installed in an ultramodern recycling facility, which would extract all uranium and plutonium together and the use of an advanced reactor to utilize these elements directly for power generation simultaneously.
The new technology will ensure that NuclearRUS can combine the most complex electrometallurgical separation and consume the extracted elements in its fast reactors located in the site. Uranium would be separated within the first two stages and then sent directly to light water reactors. In addition, fission waste materials, plutonium and actinides would be removed.
The PUREX process for reprocessing spent nuclear fuel will be economical and therefore more competitive relative to direct disposal. It would reduce the amount of spent nuclear fuel that goes into land sitings. Thus, it will conserve space at deep disposal sites.
For NuclearRUS, the implementation of the PUREX technologies would ensure that the company reduces costs associated with deep disposal at sitings. It will have abilities to generate more electricity from waste materials. The company will exploit new opportunities because of improved economics of reprocessing spent nuclear fuel. Finally, expertise and facilities can support reprocessing needs.
If the company has existing facilities, it would be easier to modify and adapt and therefore will not require any expensive investments.
The Union of Concerned Scientists has expressed its concerns about reprocessing spent nuclear fuel. According to the Union, reprocessing is dirty, risky, and expensive. It further claims that reprocessing may not be effective because it would make it “easier for terrorists to acquire nuclear weapons materials, and for nations to develop nuclear weapons programs” (Union of Concerned Scientists n.d). In addition, reprocessing will undermine gains achieved in managing spent nuclear fuel. However, the organization has failed to note that firms that handle nuclear materials are highly regulated with stringent laws, new technologies will reduce costs significantly, and reprocessing alone does not guarantee terrorists immediate access to materials. Therefore, these are not genuine reasons to stop investment in technologies to support reprocessing activities in any part of the world.
Advantages of the proposed reprocessing method and improvements on deep disposal
Relative to other approaches, specifically the direct disposal of spent nuclear fuel, the proposed advanced PUREX process will provide many advantages and have overall effects on the final waste materials that may require disposal (von Hippel 2001). Some of the advantages NuclearRUS will achieve include:
- Long-term radioactive toxic effects will be lessened significantly. Thus, the company will reduce concerns over long-term deep disposal sitings. Perhaps these emerging benefits could influence the design for sitings and enhance public acceptance (Kraft & Clary, 1991).
- The reduced quantity of waste materials will lessen the long-term generation of heat in the siting. The amount of heat generated normally corresponds to the weight of the package.
- Low volumes of generated waste materials shall reduce complexity and designs of land sitings
- The plant will have improved flexibility to spend most of its uranium and other materials
- It would reduce discharge on the environment
- Occupational exposure during facility maintenance will be significantly reduced
- Reduce overall waste volumes because of active reprocessing and recycling of both high and low radioactive materials
- New technologies will simplify the processes involved in reprocessing. Perhaps only two critical stages will be required.
- The process will enhance safety at the facility, enhance proliferation resistance because of real-time monitoring and accounting for all spent nuclear fuel.
Despite these advantages, PUREX reprocessing will still have to account for some notable concerns, such as:
- Ability to produce plutonium combined with uranium, not alone
- Traces of actinides and fission elements with a longer lifetime
- Initial costs of investments could be extremely high for new facilities
- Constant improvements to develop fuels for future advanced nuclear reactors
Although it was established that the current state of “nuclear reprocessing was not entirely viable from a political and environmental view, new technologies showed potential for the use of reprocessing in the near future” (Kenul et al. 2010, p. 1; Olander 2009).
Any approvals required
The Office for Nuclear Regulation (ONR) will independently assess the safety and security of the proposed PUREX process for reprocessing to utilize further U/Pu/Am from spent nuclear fuel (Office for Nuclear Regulation n.d).
The ONR will evaluate all existing facilities, including “the existing fleet of operating reactors, fuel cycle facilities, waste management and decommissioning sites” (Office for Nuclear Regulation n.d) and other relevant activities related to the work of NuclearRUS. In addition, it will focus on “the design, construction of new nuclear facilities, the transport and safeguarding of nuclear and radioactive materials” (Office for Nuclear Regulation n.d).
NuclearRUS is expected to cooperate with the ONR or any other bodies during these procedures, may work in collaboration to address common concerns, and conduct associated studies if necessary (Nuclear Energy Agency 1991).
The ONR does its work with rigor, diligence, and optimal levels of assurance based on the extent of the work and risk levels at the facility. On this note, it is expected that the proposed advanced PUREX for NuclearRUS must meet all the quality and safety standards before it can be deployed at the company for operations.
Cost of the facility
Estimated reprocessing costs
|Plutonium fuel fabrication cost||$1500/kgHM|
|Disposal of HLW from UOX (PUREX)||$185/kgiHM|
|Reprocessing higher-plutonium-content FR fuel||Zero charges|
|Storage of separated plutonium or removal of americium||Zero charges|
|Security, licensing, or shut-down expenses for the use of plutonium fuels in existing reactors||Zero charges|
|Cost for manufacturing higher-plutonium-content FR fuel||Zero charges|
|Operations and maintenance costs for FRs, compared to LWRs||Zero charges|
The actual cost for implementing the product could be far more complex to comprehend based on the customization that may be required by the company to meet its unique needs alongside standard operating procedures. Other variables such as complete separation and waste transmutation may also result in significantly higher costs. NuclearRUS must make cost assumptions to control them in practice, but not compromise the quality of the process.
Once the facility is installed, NuclearRUS may even reprocess spent nuclear fuel from other countries such as Japan. It is noted that the cost of reprocessing has significantly increased since 1995 (Matsuura 2013).
Comparison with other methods
There are also other reprocessing techniques such as CARBEX Process (Stepanov et al. 2011), which is not widely used in the industry and geological direct disposal, which has its drawbacks.
It is imperative to recognize that these techniques are selected based on the complexity, risk levels, expertise, facility availability, and types of spent nuclear fuel. Thus, no single method or technology can be touted as a perfect solution for spent nuclear fuel reprocessing (Simpson & Law 2012).
The challenge of handling spent nuclear fuel is common in most facilities. In this proposal, the advanced PUREX was proposed to help NuclearRUS to reprocess or utilize further its U/Pu/Am from spent nuclear fuel.
It is noted that the process will provide many benefits over direct disposal, enhance sustainability and energy security. It is widely used and therefore the required technologies and expertise are available. Any potential challenges with the proposed PUREX will be managed through developments in new technologies, process oversights, and regulation (Bodansky 2006).
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